#define _CRT_SECURE_NO_WARNINGS 1
#include <cmath>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include<math.h>
#include<stdlib.h>
#include<stdio.h>
#include<unordered_map>
using namespace std;

class Solution {
public:
    string convert(string s, int numRows) {
        if (numRows == 1) return s;
        int d = 2 * numRows - 2;
        string ret = "";
        int n = s.size();
        for (int i = 0; i < n; i += d)
            ret += s[i];
        for (int k = 1; k < numRows - 1; k++)
        {
            for (int i = k, j = d - k; i < n || j < n; i += d, j += d)
            {
                if (i < n) ret += s[i];
                if (j < n) ret += s[j];
            }
        }
        for (int i = numRows - 1; i < n; i += d)
            ret += s[i];
        return ret;
    }
};
int main() {
    return 0;
}